Patent GB-1489019-A (GB)
Title: Adaptive control system for automatic transmission
IPC: F16H61/06
Filed: 1975-06-13
Abstract: 1489019 Change-speed control CHRYSLER CORP 13 June 1975 [14 June 1974] 25412/75 Heading F2D Servo means controlling ratio-establishing engaging and disengaging devices, e.g. clutches or brakes, in an automatic transmission are controlled during a ratio shift such that during a part of the shift a component of the transmission is held in a state of incipient slip, the component repeatedly being allowed to slip in a rearward direction and then being brought to rest in a manner such that a curve of its rotational speed plotted against time is of undular form. The invention is described applied to a transmission driven through a torque converter A and comprising planetary trains providing three forward ratios and reverse. A first planetary train 15 has a sun 31 connected to a drum 23 and to the sun 29 of a second train 13, a ring gear 45 connectible to the input shaft 9 by a forward drive clutch C1, and a planet carrier 51 connected with the output shaft 43 and with a ring gear 41 of the second train. The planet carrier 35 of the latter is controlled by a brake B1 and a one-way brake 39. The drum 23 may be held by a brake B2 or connected to the input shaft by a clutch C2. Low ratio is established by the clutch C1 in combination with the oneway brake 39 or with the brake B1, intermediate ratio by the clutch C1 and brake B2, and high ratio or direct drive by the clutches C1, C2. The clutch C2 and brake B1 establish reverse. An exciter ring 61 on the drum 23 coacts with a sensor 63 to generate a signal indicative of the rotational speed of the drum 23 and this signal, after conversion at 69 to, e.g. square-wave form and passage through a filter 71, is delivered to a logic module 75 and to a differentiator 73 which delivers an acceleration signal to a comparator 77. The speed signal may be combined with a further speed signal derived from a sensor SA on the output shaft 43. Also fed to the logic module are signals representative of the settings of a gear selector 79 and engine throttle 80. These signals, together with the speed signal and an operating gear ratio signal within the logic module, are combined to establish a desired acceleration level which is compared at 77 with actual acceleration. Difference signals are fed via the logic module to solenoid valves 81, 83 controlling hydraulic servos 57, 55 which actuate the brake B2 and clutch C2 respectively. When vehicle speed at a particular throttle opening demands, e.g. a 1-2 upshift pressure fluid is supplied from a controller (not described) through a conduit 100, 97 to the servo 57 to apply the brake B2, and the flow to the servo will be unimpeded until the rate of deceleration of the drum 23 exceeds the desired rate, whereupon the solenoid valve 81 will be energized to cut-off the supply to the servo, and possibly open a vent 113, so that the brake application is eased and the rate of deceleration brought below the desired level. The solenoid valve will then be de-energized to reopen the conduit 100, 97, and this alternating action of the solenoid valve will continue, keeping the mean deceleration at the desired value, until the drum 23 is brought to rest whereupon the pressure applied to the servo increases to line pressure. During the 2-3 upshift, involving release of the brake B2 and engagement of the clutch C2, the apparatus operates in two stages. In the first stage the solenoid valve 81 is energized to release pressure from the servo 57 but is again de-energized as soon as the drum is released sufficiently to start to turn, which will be in the reverse sense. The valve 81 will thereafter cycle to hold the drum in this state of incipient reverse rotation or slip until, at the commencement of the second stage, pressure has built up in the clutch servo 55 sufficiently to impart forward drive to the drum. The pressure supplied to the clutch servo also acts in a chamber 95 to hold the brake released, and the solenoid valve 83 cycles to control the pressure in the clutch servo to obtain the desired rate of acceleration of the drum in the forward direction. The solenoid valve 83 acts in a similar manner to control deceleration of the drum during the 3-2 downshift, and as the drum comes to rest the brake B2 is applied rapidly by the servo 57. The exciter ring 61 may alternatively be mounted on the input shaft 9, on the planet carrier 35, or on some other suitable rotary part of the transmission.